Refining hydrocarbon oils



Patented Aug. 24, I943 UNHTED STATES assists GFHQE REFINING HYDROCAR/EONOILS poration of Delaware No Draining. Application December 26, 1940,Serial No. 371,779

9 Claims.

This invention relates to an improved process for refining hydrocarbonoils or waxes. More particularly, it is concerned with the treatment ofoils of the white oil type, such as medicinal oils, transformer oils,insecticide base oils, refrigerator oils and cosmetic oils, orlubricating oils, such as spindle oil and motor oil, or petroleum waxes,which have during the process or" their refinement been subjected to theaction of concentrated sulfuric acid or fuming sulfuric acid.

Heretofore, highly acid-treated oils or white oils were prepared by thedrastic treatment of a hydrocarbon oil having a viscosity in the rangeof 30 to 1000 seconds Saybolt at, 100 F. with fuming sulfuric acid,followed by separation of the acid sludge from the oil, neutralizationof the acid oil with an alkali, substantial removal of the oilsolublesulfonic acid salts or mahogany soaps from the oil by water washing orby dilute alcohol or other solvent, and steaming of the oil to removethe solvent or other volatile constituents. The oil at this stage isknown as a neutral oil and may vary in color from about l0 to +20Saybolt. The colored material remaining in the oil may be hydrocarbon innature where the conditions or amount of acid treatment used was mild,or may be due to small amounts oi organic sulfonic acid salts which aredihicult to remove by washing. The neutral oil is then finished bycontacting with adsorbent clay fines or adsorbent carbon or materials oflike nature, such as bauxite or various zeolites, or the oil may befinished percolation through a bed of adsorbent clay or carbon or thelike to give a waterwhite finished white oil of a +30 up Saybolt color.

In the refining of waxes to improve their color and stability towardsheat and light, substantially the same procedure is used as in therefining of oils except that the temperatures used are generally higherin order to keep the Wax fluid.

Many oils When finished are, however, corro sive in character and willcause the discoloration of .copper in less than two hours when subjectedto the copper strip test. This test, consists in polishing a strip ofthin copper sheet measuring X 3" with tripoli, fine steel wool, or otherfine abrasive, immersing the copper strip in a sample of the oil to betested and heating for from 2 to 3 hours in a steam bath at atemperature of 212 F. The results are rated numerically as follows: No.1 shows no change in appearance of the original copper strip; No. 2shows a slight discernable yellow color but is still passable; No. 3which does .not pass (D. N. 19.), shows a pronounced bronze coloration;No. l shows a deep bronze to red color and No. 5 is blue-black. Inseverely corrosive oils the copper may have a peace-cl: hue changing toa brassy or silvery appearance.

In testing the corrosive charac er of refined waxes, the same procedureis used except that a temperature of 300 F. and a time of 10 hours areused.

Oils and waxes which exhibit a poor response to the copper testgenerally also showpoor stability toward heat and light. On exposure ofrefined oils and waxes to either natural sunlight or toward artificiallight which is rich in ultraviolet rays, such as carbon arc or mercuryvapor lamps, the oil or wax, if not perfectly refined and free fromobjectionable by-products, may develop disagreeable odors and tasteswhich are generally described as garlic, l-lzS, cedar and, in bad cases,rancid. Waxes are less prone to develop distinctive odors other than ageneral rancidity but may quickly go off color.

Ordinarily, oils andwaxes which have failed to pass the copper striptest have had to be recycled through the acid treatment in an attempt tomake them less corrosive. At times it has been necessary to recycle thecorrosive oils through the acid treatment three or four times before anaccepta ole copper strip test obtained upon them.

Some success has been had in treating finished white oils or waxes toimprove their copper strip test by the use of calcium or magnesiumhydroxide. However, this method is not generally applicable to medicinalwhite oils because oils treated with these reagents acquire anobjectionable taste. Also, the quantity of calcium and magnesiumhydroxide used is bulky and its removal necessitates additional handlingof the finished oil which increases the possibility of contamination. Inaddition, there are individual cases of corrosive oils when, in order toobtain good copper strip tests by the use of calcium or magnesiumhydroxide, it has been necessary to give the oil several teratments withthese reagents.

In addition to the above method, which works best on finished whiteoils, 2. number of methods have been in use for correcting corrosiveoils to improve their copper strip test by chemical treatment of theneutral oil prior to final percolation through clay. For example, it hasbeen found that alcoholic potassium hydroxide in the proportion ofone-half to ten pounds of the dry hydroxide per thousand gallons of oilaffords some degree of correction when added to the neutral oil at theend of the steaming period, but this method of treating corrosive oilshas several notable objections, the chief among these being the severdegradation in color which takes place and the tendency for the finishedwhite oil from the clay percolating filters to run cloudy after acompartively short filter life.

According to the present invention, it has been found that ifsubstances, such as the various diatomaceous filter aids, or finelyground activated carbon, are added to the neutral oil, after it has beentreated with alcoholic KOH or NaOl-I at 100 C. to 150 0., and thealcohol removed by blowing with air or inert gas, and subsequentlyfiltered to remove the diatom-K011 complex, the neutral oil can then befinished by contacting with adsorbent clay fines or adsorbent carbon, orby percolation through a bed of adsorbent clay or carbon or the like togive a finished white oil of a +30 up Saybolt color which passes thecopper test and which comes through the percolation filter without theappearance of any cloudiness'or haziness even after 20 times the amountof oil has passed through the clay bed as was obtained without the useof the diatomaceous earth or activated carbon.

In practicing the present invention, the neutral oil is brought up tothe working temperature of 100 C. to 150 C. by means of a convenientsource 'of heat,-such as a steam coil or by passage through a heatexchanger, and in the case of the heavier oils which may have some wateremulsified or suspended in the oil, is previously dried by air-blowingfor a short time. When the oil is substantially dry, an alcoholicsolution of potassium hydroxide containing from one-half pound to lbs.of dry KOH per thousand gallons of oil treated is added to the oil andthoroughly mixed to effect solution. At the temperatures used, most ofthe alcohol is evaporated off in a short time and recovered through acondenser. The remainder ofthe alcohol is removed by air-blowing whenthe process is operated in a batch still, but it is possible to removethe alcohol by passing the oil downward through a packed tower whileblowing countercurrently with a stream of air or inert gas, or the oilcontaining the KOH and alcohol may be passed in a thin film through orover a heated zone while maintaining a vacuum in the region of theheated zone.

When all of the alcohol has been removed, the alkaline metal hydroxideis dispersed throughout the oil in the form of a colloidal suspension. tis believed that the action of the KOH on the corrosive principlespresent in the oil is a surface phenomenon, in which the KOH forms aninsoluble complex with the corrosive material present, and it istherefore within the province of this invention to add the KOH to theoil in the form of a colloidal dispersion in a nonaqueous medium, suchas a finished oil of the same viscosity as the oil being treated or ananhydrous solvent like glycol.

After all of the alcohol has been removed, the oil is cooled to atemperature of from C. to 10 0" 0., preferably C. and then treated witha quantity of filter aid or activated carbon in an amount equal to from1 lb. to 40 lbs. per thousand gallons of oil. The amount added ispreferably from 2 to 4 times that of the weight of dry alkali hydroxideused. Most types of diatomaceous filter earths commercially availableare suitable for the practice of this invention, particularly thosewhich fall into the following classification: The natural air dried andground earths, calcined and ground earths, earths calcined in thepresence of alkali and the acidtreated earths. The types of activatedcarbon which may be used may either be of the natural or acid-treatedvarieties.

The method of treating the KOI-I treated oil with the diatoinaceousearth or carbon may be varied from either the direct addition of thesematerials to the oil in the form of a dry powder or they may bepreviously admixed with a portion of the oil to form a slurry which canthen be pumped into the main body of the oil The diatomaceous earth,after it has been added to the oil, may be agitated for a period of from5 minutes to Z hour and then filtered through ther a plate and framepress, a continuous H-tary press, or may be centrifuged out by means ofbasket type of centrifuge. In using the plate and frame or rotary typeof press, it is advantageous to precoat the press with from 5 to it lbs.of the diatomaceous filter aid per hundred square feet of filter pressarea. The oil so obtained is optically bright and free from haze and isseveral shades of color lighter ran the original KOH treated oil. Theoil is then finished by contacting with or percolation through asorptive material, such as Attapulgus clay, activated carbon, bauxite ornatural or synthetic zeolites. The expression sorptive material is usedto denote those materials which are either active by adsorption or byabsorption such as are enumerated above.

The invention will be more clearly illustrated by the followin example:

EXAMPLE i) gallons of an acid-treated neutral white oil having aviscosity at 100 F. of 55 seconds Saybolt was treated at a temperatureof C. with 5 lbs. of KOH dissolved in substantially anhydrous alcohol.After the addition of the KOH was complete, the oil was air blown untilfree from alcohoi. The oil was then transferred to an agitator, cooledto 50 C. and 20 lbs. of a diatomaceous earth filter aid (commerciallyknown as J-N Standard Super-Gel) was added and the mixture agitatedwhile maintaining the temperature of 50 C. for period of 15 minutes. Theoil was then filtered through a plate and frame press which had beenpreviously precoated with the same filter aid in an amount equal to 5lbs. of filter aid per hundred square feet of filter press area.. Afterthe oil had cooled to atmospheric temperature it was percolated througha bed of adsorbent Attapulgus clay to yield a finished white oil. Thisresulting oil gave a satisfactory copper test and improved stabilitytoward sunlight. The following table gives the comparative data on theoriginal neutral oil without KOH treatment, the same oil treated with 5lbs. of KOH per thousand gallons of oil but without filter aid, and theoil prepared according to the above example:

and. filtering, and then passing the hydrocarbons through a sorptivematerial.

Table Neutral 011 Neutral 0i1+A1c-KOH Neutral ig a acmding Neutral oilcolor +17 Saybolt +8 Saybolt +20 Saybolt. 1 hr. neutral oil copper DNP 14--- DNP Pass 1. 2 hr. neutral oil copper- DNP d0 Pass 1-2. 3 hr.neutral oil copper do do. Pass 2. Color after percolation +30 up Saybo+19 Saybolt (hazy +30 up. 1 hr. copper test after percolation NP 4- DNP3 (sp0tty) Pass 1. 2 in. copper test after percolation"- DN]? 5... 0 D0.3 hr. copper test after percolation do DN 4 (spotty) D0. Taste and odorafter percolation Garlic and rancid. Metallic Pass test 5 min. naturalsunlight stability DNP H23 Do- 1 DNP is abbreviation for Does not pass.

What is claimed is:

1. The process of improving the color and reducing the corrosiveness ofacid-treated petroleum hydrocarbons having a viscosity in the range offrom 30 to 1000 seconds Saybolt at 100 F. on copper which comprisestreating the hydrocarbon in its neutral state first with an alkali metalhydroxide at 100 C. to 150 C., cooling the hydrocarbon to from C. to 100C., adding a finely divided diatomaceous filter aid, agitating andfiltering.

2. The process of improving the color and reducing the corrosiveness ofacid-treated oils on copper which comprises treating the oil in itsneutral state first with an alkali metal hydroxide at 100 C. to 150 C.,cooling the oil to "from 20 C.

to 100 C., adding a finely divided diatomaceous filter aid, agitatingand filtering.

3. The process of improving the color and reducing the corrosiveness ofacid-treated petroleum hydrocarbons having a viscosity in the range offrom to 1000 seconds Saybo-lt at F. on copper which comprises treatingthe hydrocarbons in their neutral state first with an alcoholic solutionof an alkali metal hydroxide at 100 to C., removing the alcohol, coolingthe hydrocarbons to from 20 to 100 0., adding a finely divideddiatomaceous filter aid, agitating and filtering.

4. The process of improving the color and reducing the corrosiveness ofacid-treated oil on copper which comprises treating the oil in itsneutral state first with an alcoholic solution of an alkali metalhydroxide at 100 C, to 150 C., removing the alcohol, cooling the oil toa temperature between 20 and 100 C., adding a finely divideddiatomaceous filter aid, agitating and filtering to remove adiatom-alkali metal hydroxide complex from the oil.

5. The process of improving the color and reducing the corrosiveness oiacid-treated petroleum hydrocarbons having a viscosity in the range offrom 30 to 1000 seconds Saybolt at 1000 F. on copper which comprisestreating the hydrocarbons in their neutral state first with an alkalimetal hydroxide at 100 to 150 C., cooling the hydrocarbons to from 20 to100 C., adding a finely divided diatomaceous filter aid, agitating 6.The process of improving the color and reducing the corrosiveness ofacid-treated oils on copper which comprises treating the oil in itsneutral state first with an alkali metal hydroxide at 100 C. to 150 C.,cooling the oil to from 20 C. to 100 C., adding a finely divideddiato-maceous filter aid, agitating, filtering and passing the oilthrough a sorptive material.

7. The process of improving the color and reducing the co-rrosiveness ofacid-treated petroleum hydrocarbons having a viscosity in the range offrom 30 to 1000 seconds Saybolt at 100 F. on copper which comprisestreating the hydrocarbons in their neutral state first with an alcoholicsolution of an alkali metal hydroxide at 100 to 150 C., removing thealcohol, cooling the hydrocarbons to from 20 to 100 C., adding a finelydivided diatomaceous filter aid, agitating, filtering and then passingthe hydrocarbons through a sorptive clay.

8. The process of improving the color and reducing the corrosiveness ofacid-treated oil on copper which comprises treating the oil in itsneutral state first with an alcoholic solution of an alkali metalhydroxide at 100 C. to 150 C.,

.- removing the alcohol, cooling the oil to a temperature between 20 and100 0., adding a finely divided diatomaceous filter aid, agitating andfiltering to remove a diatom-alkali metal hydroxide complex from the oiland then passing the oil thru a sorptive clay.

9. The process of improving the color and reducing the corrosiveness ofacid-treated oils on copper which comprises treating the oil in itsneutral state first with an alcoholic solution of potassium hydroxide inan amount equal to from CHARLES A. COHEN.

